Energy Transfer and Chiroptical Transfer in Silylene-Spaced Divinylarene Copolymers
Date Issued
2004
Date
2004
Author(s)
Cheng, Yen-Ju
DOI
en-US
Abstract
A series of regioregular silylene-spaced alternating [(donor-SiMe2)n=1-3-(acceptor)-SiMe2] copolymers was synthesized by rhodium-catalyzed hydrosilylation of bis-alkynes with bis-silylhydrides. The ratio of donor to acceptor can be well controlled by appropriate design of the monomeric precursors. Bis-silylhydrides were prepared by nickel-catalyzed olefination of the corresponding aryl dithioacetals with Grignard reagent followed by LAH reduction. Two-donor bis-alkynes were obtained by Heck reaction followed by subsequent Sonogashira or Kumada-Corriu reaction. The synthesis of three-donor bis-alkyne was based on hydrosilylation of two different donor precursors. Unlike most copolymers, our strategy has furnished a powerful arsenal for the construction of copolymers with precise regiochemistry and repetitive units. Monomeric reference compounds having similar chromophore components were also prepared for photophysical comparison. The silylene moieties serve as insulating building block between chromophores. No excimer-like formation has been found in these types of polymers with relatively long conjugation chromophores. The effect of photoinduced electron transfer plays a negligible role in these polymeric systems. No emission coming from donor was observed in fluorescence spectra, illustrating that intrachain energy transfer is highly efficient along the polymeric chain. The polymers exhibit light-harvesting ability and the intensity of emission spectra are enhanced with the increasing number of donor to acceptor ratio. Upon excitation of these copolymers at UV wavelengths, versatile colors of light from acceptors via energy transfer can be accessed by incorporating well-designed
Subjects
Energy Transfer
Silylene-Spaced
Chiropitcal Transfer
能量轉移
手性光學轉移
矽烷基為間隔
Type
thesis
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